Mammaries, Sour Grapes Flashcards
What is mastitis?
Inflammation of the mammary gland with chemical and microbial changes, with increased leukocytes
2 types of mastitis
Cow associated -> source is infected mammary gland, severity depends on virulence factors
Environmental -> contamination of teat ends or intra-mammary tubes, mainly occur during drying off and in the weeks
before calving, likely to be clinical
3 bugs in environmental mastitis
- Streptococcus uberis (faeces,
exotoxins) - Streptococcus dysgalactiae (faeces, exotoxins)
Both strep are gram positive
- Escherichia coli (coliform) - gram negative, in faeces, endotoxins when killed
Others -> trueperella pyogenes, pseudomonas aeruginosa
4 bugs in cow associated mastitis
Strep agalactia (frequent - only lives in mammary gland and human skin <6d)
Strep aureus (common) - skin, can live inside WBC’s and escape antibiotics
Mycoplasma bovis - lives everywhere
Corynebacterium bovis - causes abscess, lives on skin
Staph species minor pathogen
Pathogenesis of mastitis
Organism invades udder through teat canal
Migrates up canal and colonize secretory cells
Colonized organisms produce toxic substances harmful to the milk producing cells
Immune system reaction -> somatic cells
How long is teat suscpetible for after milking?
up to 30 mins the teat remains open
Trigger points for action in mastitis
5 clinical cases per 100 cows calved
> 15DIM = More than 2 clinical cases/100 cows in milk/month
Post milking teat disinfection guidelines
Mixed fresh daily with high quality water - dont top up when low, replace it
Emollients used like glycerin (never >10%), glycan, sorbitol
0.5% iodine solution
Ensure all surfaces dipped
Good hygiene practices
Avoid milk on hands and disinfect all milk from machinery, liners, people
Milk high cell count cows last
Water for cleaning - quality (soft), temperature, concentration, quantity to be sufficient to ensure all surfaces cleaned
Good drainage in cleaning cycle - reduce microbe contamination
Maintenance of machine
How often should liners be changed?
every 2000 milkings
How many milkings of colostrum should be discarded from the vat?
first 8 milkings or 10 for induced cows
Data that should be monitored in dairy
BMCC results
Milk collection temperatures
Atypical events - water, chemicals
Errors - human or otherwise
History of milk quality
Cleaning routine specifics
Plant inspection details
Strategic milk sampling
Different aspects in a mastitis herd health visit
Farm profile
Milk cultures
ICCC
Milking machine dry time
Performance tests of machine
Clinical cases
Teat condition
Cow behaviour
Teat disinfection
The environment
What number of ICCC is unlikely to have subclinical mastitis? WHen is she clinically affected?
<150,000 cells/ml unlikely
20-100,000 is normal
> 250,000 is clinical and above 400 is unfit for human consumption
What is the californian mastitis test?
Cow-side test which is used to assess the somatic cell count of the milk for cows in all four
quarters. It can be used to test for efficacy of treatment after a bout of mastitis, or to double check a cows ICC
California milk test method and scoring
- Discard the foremilk
- 2 squirt from each quarter into the cup
- Add equal volume of CMT reagent
- Swirl and look for reaction in 8 seconds
Scoring:
0 is negative -> 0-200,000 cells and 0-25% neutrophils
T is trace (slight precipitate) -> 100-500 thousand and 30-40% neutrophils
1 is weak positive (precipitate but no gel) -> 400 to 1.5million cells and 40-60% neutrophils
2 is positive (gel) -> 800 to 5 million cells, 60-70% neutrophils
3 is strong positive (viscous gel) -> >5 million cells, 70-80% neutrophils
How long are californian mastitis test results valid for?
2h as leucocytes degenerate
Drying off guidelines - rate of reducing milk production + feeding
Dry off between 5-12L a day and reduce production to <12L a day by reducing feed intake to maintenance
Put into a clean paddock
Adminstering dry cow therapy guidelines
Identify udders of dry cows
Record cow ID, date and product
Allow for 20 cows/h
Sanitise the teat end after treatment
Minimise leakage by reducing walking and activity
Look for swollen quarters in the paddock, for heat and pain, only strip the problem quarter
When to cull cows with mastitis
Cows with 3+ clinical cases of mastitis during a lactation
A high ICCC during the previous lactation where she was dry cow treated and continued to have issues this lactation
Economic losses due to mastitis
Loss of milk production = discarded and WHP for antibiotics
Fibrosis of udder
Penalties for high SCC
Cost of vet, death in peracute cases, premature culling of cows
Treatment plan for peracute case of mastitis
IVFT - sepsis
NSAID
Tylosin - macrolide for mycoplasma, similar to erythromycin but less active against gram negatives.
Erythromycin - macrolide, lipid soluble. Good for gram positives. Resistance in mycoplasma bovis.
Trimethroprim + sulphonamide - macrolides. Not for mycoplasma. At low doses struggles to get to mammary gland. Gram negative efficacy
Treatment plan for acute mastitis
Tylosin - mycoplasma
Erythromycin - gram pos
TMS - gram negatives, multiple quarter infections
Chronic mastitis treatment
dry cow therapy
What is selective DCT?
When only cows with history of elevated ICCC or clinical mastitis get antibiotic therapy at dry off
Administered at last milking of lactation
How much does each clinical mastitis case cost?
300-400
What cows should samples be taken from if clinical cases are the presenting problem, or if high cell counts are the problem?
Clinical cases -> all cases as they are detected
high SCC -> selection for sampling based on mastitis history or recent ICCC
ICCC analysis purpose + unacceptable rate of new infection for heifers
What classifies a persistent infection?
Estimate rate of new infection in herd, get an idea of age/stage of lactation or management in all groups
Get proportion of cows above 250,000 in each group
Unacceptable rate of new infection is more than 20% of heifers being above 250,000 by end of 1st lactation
Estimate number of persistent infection -> above 250 in last and this lactation
Identify cows for foremilk stripping
How manny ICCC should be taken in a lactation?
At least 5 to get an idea of status of cow during a lactation
What does a california mastitis test use for reagent?
Alkyl arysulfonate and bromcresol purple
Lysis cells and polymerises DNA - the more gel the more DNA from nucleated cells
Milk fat %
Milk protein %
3.2-4.8 for fat
2.9-3.2 for protein
Milk protein to milk fat ratio
0.85 ideal
protein to fat ratio indicative of SARA
> 0.95
protein to fat ratio indicative of ketosis
<0.75
Fermentation sites in cows
Rumen
Caecum
Colon
Factors for microbial growth
pH close to neutral 6-7
Temp 39 degrees
Rate of flow - slow enough for multiplication of microbes
Major microbes
Bacteria
Protozoa
Fungi
Methanogens
Bacteriophages
Symbiotic relationship between rumen microbes and cows
Digestion of cellulose and hemicellulose
Provide high quality protein + B vitamins
Detoxification of toxic compounds
end product of anaerobic microbial metabolism - VFAs
3 VFAs and what increases them
Acetate -> increased with high fibre
Propionate -> increased with high starch
Butyrate -> varies with diet
What does accumulation of VFAs result in?
Decreases pH and suppresses fermentation
Host animal maintains conditions for fermentation by buffering with saliva and removing VFAs via absorption through rumen papillae
Sources of protein
True protein and non-protein nitrogen (urea)
Urea cycling process
NOn-protein nitrogen sources - nitrate, urea, ammonia
Urea is a nitrogenous waste product formed in the liver
Monogastric - excreted in kidneys
Rumen -> excreted into rumen via blood or saliva and used in protein production
What vitamins do bacteria make in the large intestine?
most of required vitamins
K and B produced by colonic bacteria
Non-fermentative function of large intestine
Absorption of water and electrolytes
Net absorption of H20, Na, Cl and bicarb and net secretion of K+
Aetiopathogenesis of acidosis
Excessively rapid fermentation of excess carbohydrate, causing a shift in VFA metabolism and a decrease in rumen pH
Accumulation of lactic acid due to lactobacillus and strep bovis which become predominant species in pH <5 = ruminal acidosis, metabolic acidosis
Saliva buffering requires enough roughage and particle size
SARA = accumulation of VFAs but not lactic acid
Rumenocentesis of acidotic cow
Milky green-brown
pH <5
Clinical signs of ruminal acidosis
Anorexic, dull, ataxic, colic, tachycardic, splashing sounds, profuse water light green diarrhoea, enophthalmos, decreased feed intake
Treatment of ruminal acidosis
Left flank laparotomy to remove rumen fluid
Transfaunation of rumen fluid from healthy cow
IVFT
Treat metabolic acidosis if present
Antimicrobials > procaine pen G to prevent rumenitis, bacterial hepatitis and formation of liver abscesses
Vitamin B
Treatment of lameness
Hoof trimming
foot wedges to take weight off problem claw
If infected, treat
Risk factors for lameness
Poor dairy enterance
rough surface
long walking distances
nutrition
wet ground
6 major causes of lameness
- White line disease
- Sole injury
- Sole bruising
- Axial wall crack
- Footrot
- Digitial dermatitis
Pathophysiology of white line disease
Separation of the wall from the sole
* Caused by pressure and poor cow flow leading to cows twisting and turning on hooves
* Mechanical injury from abrasive surfaces
* Wet conditions soften claw horn
Treatment of white line disease
- Pare away wall, remove underrun hoof
- Create drainage by smoothing edges of pared area so dirt cannot pack in
- Lift weight off affected claw by placing block/cowslip on unaffected claw
- Treat with antibiotics or NSAIDs if required
Sole injury pathophys
Sole penetration
Sole abscess
Underrun sole
Sole injury treatment
- Remove all underrun sole and any hoof wall underrun by abscess
- Create drainage hole, but make
sure no gravel/dirt can get trapped - Apply cowslip or block to unaffected claw
- Treat with antibiotics or NSAIDs
hh
Sole bruising at risk cows and treatment
first calvers
If one claw affected, apply cowslip to unaffected claw
If both claws affected, keep animal close to shed
Axial wall crack pathophysiology
A crack in the inside of the claw at
the join of the hoof wall and the
sole.
* Overgrown toes
* Uneven walking surfaces
* Corkscrew claws
* Traumatic injury or disease
Axial wall crack treatment
Pare underrun hoof wall in axial groove to prevent formation of proud flesh
Place cowslip or block
Digital dermatitis pathophysiology
- Infection of the digital/interdigital skin
- Most commonly caused by
Spirochaetes but many
bacteria have been implicated - Water, mud, urine and faeces
- Presence of bacteria
Cow to cow via environment
Digital dermatitis treatment
Clean ulcer
Dry and spray with antibiotic spray (oxytetracycline) and let dry and repeat
Hygiene of herd and dairy
Good biosecurity protocol
Regular foot baths (copper sulfate)
Footrot pathophysiology - interdigital necrobacillosus
Bacterial infection in
interdigital space
pungent odour, symmetrical swelling, interdigital skin necrosis
Mixed bacterial infection
Footrot treatment
Investigate interdigital space
Clean the cleft and remove foreign objects or dead tissue
Spray the cleaned cleft with an
antiseptic/iodine
Check claws for other lesions
Antibiotics
Advice for reducing lameness
- Rubber laneways
- Avoid walking cows long distances
- Keep the dairy dry
- Make sure the stocking density isn’t so high that the cows are standing in manure
- Have good biosecurity to prevent digital dermatitis entering the farm
Data required for fertility monitoring
Calving - dystocia, caesar, dead
Oestrus - where no serve occurs (VWP)
Service - sire, AI/natural, inseminator
Pregnancy diagnosis result
Other fertility vet exams
Metrtitis
Endometritis
Abortion
When should fertility visits occur?
Every week or fortnight
What things could deem a cow as needing action on a fertility visit?
Post natal checks at 21d PP
Vulval discharge
Oestrus not observed by specfic stage of lactation -> eg 24d after VWP
Pregnancy diagnosis
Repeat breeder cows
Cows overdue
What is the herd calving index?
Average of calving intervals in the herd - commonly used as measure of overall performance
Useful indicator of long term performance but poor monitor when used alone -> retrospective and influenced by culling stratgey
What does the proportion of pregnancy diagnosis that are positive tell us?
Detection of returns to service, and gives an idea of pregnancy rate
Should be >80% in herds where pregnancy rate is >40%
What does the number of cycling cows presented as ONO at each visit tell us?
Heat detection - especially for cows due for first service
What does calving to conception interval provide
Similar info to calving index but less retrospective as the end point successful service marked by pos preg test (occurs far sooner than next calving as in calving index)
How long is pregnancy
280d
What does submission for service encompass?
Oestrus expression and detection as well as post partum return to cyclicity
What is the first service submission rate?
Proportion of cows receiving first service within 24d of becoming eligible (eg after VWP)
Most cows should have oestrus within 24d of VWP
What is the return to service submission rate?
proportion of failed serves (not leading to preg) which a subsequent serve occurs 18-24d later
Should be lower than first service submission rate
What is clinical metritis characterised by?
Purulent uterine discharge with abnormally enlarged uteris within 21d calving but no other clinical signs
Factors affecting oestrus expressoin
Lameness
Pain
Stress
Mastitis
High yielding cows - express for less time or less intensely
Non-slip, squishy floors - help
Prefer outdoor loafing for oestrus behaviour rather than inside
Time spent in milking -> 3x a day, less time for oestrus more time in holding yards
How much loafing area is required for each cow?
2-3m2 per cow minimum
How does NEB affect pregnancy rate?
Risk factor for retained fetal membranes, metritis, ketosis, disaplced abomasum
Low IGF-1 -> decreased response of ovary to gonadotropins
When should cows be AI’d after showing first signs of oestrus?
No later than 10-12 hours later
Organisms and diseases spread through reproduction
Tritrichomonas fetus
Campylobacteriosis
Mycoplasma
Ureaplasma
IBR
BVDV
Acquiring mastitis samples
Good aseptic technique - wash and dry teats well with disinfectant, squirt 6 times and repeat
Immediately fridge or freeze
Pre-milking are more diagnostic than post milking
label tube with cow id, quarter, date
For every 100,000 cell/ml increase in BMCC, how many cows are infected?
8-10% increase in proportion of cows infected in the herd
Aims when attempting to control mastitis
Reduce prevalence of infection - number and duration of existing infection, as well as new infection
Cull chronic cows
Best chance to cure chronic cows is in the dry period
Decifer if its environmental or contagious
Mastitis investigation approach
- establish goals and herd targets
- Assess current practice and find deficiencies
- Evaluate data - SCC and clinical mastitis data from at least past 18 months to detect patterns of disease
- Determine source of infection and control measures
- Monitor outcomes
3 ways to reduce herd prevalence of mastitis infection
Dry off infected quarters
cull
treat
Things associated with poorer prognosis of cure in mastiis
Chronic high cell count
Severe teat lesions
Other health problems
Delay in initiation of treatment
Increasing parity
more than 1 quarter affected
Beta-lactamase producing s.aureus
Fibrosis of mammary gland
Define lameness
The clinical presentation of impaired locomotion
Where does most lameness occur?
Hind feet
Mostly due to claw lesions with remainder being limb lesions
4 causes of lameness
Sole ulcer
White line disease
Digital dermatitis
Interdigital necrobacillosis
Economic losses of lameness
Infertility - anoestrus or not wanting to stand
Culling
Reduction in milk yield
Treatment costs
Professional fees
Lameness scale 1-5
- Stands and walks with a level back posture; gait is normal
2 Stands with level back but arched back when walking; gait is normal
3 Arches back when walking and standing; gait is affected
4 Arched back posture always evident; gait shows deliberate steps
5 Inability or extreme reluctance to bear weight on one or more limbs
Mobility index industry benchmark
90%
Industry benchmark values for lameness score 4 and 5
0.5% for both
How often should locomotion scoring occur? What should it be concurrent with?
every 2-4wks to detect subclinical and clinical lameness
Routine evaluation of claw health, hoof trimming and abnormality detection
Why is BMCC useful to monitor herd mastitis?
Daily updates
Indirect measure of subclinical in herd - approximate infection level
Easy access to information
Sudden increase suggests a clinical case is present
Benchmark for 3-5 lameness score
10%
TCM period
3 weeks prior to 4 weeks post calving
Does DMI decrease around calving?
Yes by 30% - and more so in cows in high BCS
Which cows are more at risk of lameness?
Cows with poor BCS at calving and lactation
BCS is positively correlated with thickness of digital cushion
Methods to reduce lameness
Feed pregnant heifers a high dry matter diet and limit BCS loss prior to calving
What decreases with SARA?
Milk fat
Rumen pH -> less than 5.5 is clinical
SARA MOA
Excessive fermentation of sugars and starches with inadequate fibre and buffering of the rumen
Poor TCM, feeding high fermentable food, high starch, low fibre, excess finely ground particles
Ketosis NEFA cutoffs 2 weeks and 1 week prior to calving
NEFA increases prior to calving anyway
1 weeks prior = <0.6mmol/L (any more is a risk)
2 weeks prior = <0.3mmol/l is appropriate
Type 1 ketosis is:
where nutritional demands after calving are not met
3-6 weeks post calving
Bad yields and poor fertility
Type II ketosis is:
Associated with fatty infiltration of the liver
Elevated NEFA immediately post calving
BHB’s elevated 5d post calving
Collecting samples for ketosis
Tail/jugular
Will increase with haemolysis so separate within few hours and freeze/chill
Reasons for buffering failure
Not ruminating or chewing new food
Inadequate fibre length (5-10cm) - to form fibre mat in rumen to trap in food for microbial digestion
Feeding high fermentable foods
Poor cow comfort - less lying/ruminating time
What increases acetate?
Structural carbohydresa (cellulose, hemicellulose)
Need acetate to make milk fat
What increases proprionate?
Non-structural carbohydrates
What VFA does milk fat rely on?
Acetate
What do VFA’s do in SARA?
Propionate (from non-structural carb) = increases
Acetate = decreases = less milk fat
Prevalence of lameness score 2 for a cause of investigation
More than 5% prevalence of lameness score 2 cows is cause to investigate acidosis as a possible factor in a lameness problem
Targets for ketosis, hypocal, clinical mastitis and lameness in the herd
<3-5% ketosis and hypocal in the herd
<2-5% clinical mastitis cases a month
<5% lameness (<10% claw abnormalities)
